A resilient marine anchor

Abstract

A resilient marine anchor (11, 111, 211) is disclosed having a single fluke (13, 213) with a longitudinal axis and a generally V-shaped tip (16, 216). An upstanding lug (17, 117) extends from an upper surface of the fluke and is aligned with the longitudinal axis. A keel (14, 214) protrudes from a lower surface of the fluke and is aligned with the longitudinal axis. A shank (12, 112, 212) is pivotably mounted to the lug about a pivot axis substantially perpendicular to the longitudinal axis and is movable relative thereto to change the angle of attack of the anchor. A resilient means (28, 227) extends between the shank and the lug and is arranged to resiliently load the pivotal movement of the shank relative to the fluke.

Description

[0001] A RESILIENT MARINE ANCHOR

[0002] Field of the Invention

[0003] The present invention relates to marine anchors and, in particular, to resilient marine anchors for small vessels, yachts and pleasure craft.

[0004] Background Art

[0005] Marine anchors have long been used to temporarily moor boats. Different sea bed conditions present widely different engagement conditions for anchors. In particular, some types of seabed such as sand, gravel, and fine sediment can result in anchors pulling through the fine unsolidified material. It is even known for boats to carry two or more anchors of different design for use with different seabed conditions.

[0006] US Patent No 8, 950, 352 (Smith) discloses a marine anchor cast as a single piece in metal. The anchor has a fluke shaped like a bicycle seat and a shank rigidly attached to the fluke. As a consequence, the angle of attack of the fluke relative to the shank is unable to be varied, with the consequence that the anchor is not able to adapt to a wide variety of seabed or riverbed conditions.

[0007] Genesis of the Invention

[0008] The Genesis of the present invention is a desire to provide a marine anchor which can resiliently change its angle of attack to thereby better embed itself in fine and uncompacted seabed or riverbed materials.

[0009] Summary of the Invention

[0010] In accordance with a first aspect of the present invention there is disclosed a resilient marine anchor having a single fluke with a longitudinal axis and a generally V-shaped tip, said fluke having an upper surface and a keel protruding from a lower surface of said fluke and aligned with said longitudinal axis, a shank pivotably mounted to said fluke about a pivot axis substantially perpendicular to said fluke longitudinal axis and movable relative thereto to change the angle of attack of said anchor, and a resilient means extending between said shank and said fluke and arranged to resiliently load the pivotal movement of said shank relative to said fluke.

[0011] Brief Description of the Drawings

[0012] Some embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings in which:

[0013] Fig. 1 is a side elevation of a prior art anchor and a substantial reproduction of

[0014] Fig. 7 of the above-mentioned US patent,

[0015] Fig. 2 is a perspective view of the anchor of Fig. 1 and a substantial reproduction of Fig. 10 of the above-mentioned US patent,

[0016] Fig. 3 is a rear perspective view from above of the anchor of a first embodiment of the present invention,

[0017] Fig. 4 is a perspective view from below of the anchor of Fig. 3,

[0018] Fig. 5 is an exploded perspective view, partially in section, of the resiliently loaded pivot arrangement of the anchor of Figs. 3 and 4,

[0019] Fig. 6 is a side elevation of the anchor of the first embodiment in its initial deployment configuration,

[0020] Fig. 7 is an enlarged side view of the damped pivot arrangement of the anchor in the condition illustrated in Fig. 6,

[0021] Fig. 8 is a side elevation of the anchor of the first embodiment in its enlarged angle of attack configuration,

[0022] Fig. 9 is an enlarged side view of the damped pivot arrangement of the anchor in the condition illustrated in Fig. 8,

[0023] Fig. 10 is a schematic side elevation of the anchor of Fig. 3 during its initial engagement with the seabed or riverbed,

[0024] Fig. 11 is a schematic side elevation similar to that of Fig. 10 but illustrating the anchor further embedded into the sediment of the seabed or riverbed,

[0025] Fig. 12 is a perspective view from the rear of an anchor of a second embodiment,

[0026] Fig. 13 is a perspective view from the front of the anchor of Fig. 12,

[0027] Fig. 14 is a side elevation of the anchor of Figs. 12 and 13 at a minimum attack angle,

[0028] Fig. 15 is a side elevation of the anchor of Figs. 12 and 13 at a maximum attack angle, Fig. 16 is a perspective view from above of an anchor of a third embodiment,

[0029] Fig. 17 is a perspective view from the front and below of the anchor of Fig. 16,

[0030] Fig. 18 is a perspective view from the rear and below of the anchor of Fig. 16,

[0031] Fig. 19 is an exploded perspective view of the anchor of Fig. 16,

[0032] Fig. 20 is an exploded perspective view of the spring assembly as used in the anchor of Fig. 16,

[0033] Fig. 21 is a similar exploded perspective view to that of Fig. 20 but from the opposite direction,

[0034] Fig. 22 is a perspective view of the assembled spring assembly of Figs. 20 and 21,

[0035] Fig. 23 is a perspective view of the end of the shank closer to the fluke of the anchor of Fig. 16,

[0036] Fig. 24 is a generally longitudinal sectional view through the anchor of Fig. 16,

[0037] Fig. 25 is a schematic side elevational view of the anchor of Fig. 16 embedded in the seabed,

[0038] Fig. 26 is a similar side elevational view to that of Fig. 25 but showing an increased angle of attack,

[0039] Fig. 27 is a longitudinal cross-sectional view through the anchor of Fig. 16 with the shank in a lowered position,

[0040] Fig. 28 is a similar longitudinal view to that of Fig. 27 but showing the shank in a raised position,

[0041] Fig. 29 is a view similar to that of Figs. 27 and 28 and showing the consequence of the shank having been raised,

[0042] Fig. 30 is an exploded perspective view of a second embodiment of the spring assembly,

[0043] Fig. 31 is a perspective view of the assembled spring assembly of the second embodiment,

[0044] Fig. 32 is a rear perspective view showing the attachment of an auxiliary chain to the anchor of Fig. 16,

[0045] Fig. 33 shows two of the anchors of Fig. 16 ganged together utilising an auxiliary chain, and

[0046] Fig. 34 is a sequence of four drawings illustrating a consequence of different rode lengths. Detailed Description

[0047] As seen in Figs. 1 and 2, the prior art anchor 1 of the above-mentioned US patent has a shank 2, and a fluke 3 which has both a keel 4 and a tip 6. Since it is likely that the anchor 1 when dropped onto the seabed 7 will have an attitude as illustrated in Fig. 2, so the fluke 3 is shaped to resemble a bicycle seat. This has the effect that the tip 6 will engage with the seabed 7 and, during the initial embedding process, right the anchor 1 into the intended upright deployment attitude as illustrated in Fig. 1. In this connection it needs to be borne in mind that the chain or rode of the anchor is attached to the free end of the shank 2 and pulls the anchor to the left as seen in Fig. 1. As a consequence of this movement, the tip 6 of the fluke 3 presents an angle of attack A of approximately 10-15° which drives the fluke 3 deeper into the seabed 7.

[0048] However, the seabed 7 normally either consists of, or contains a substantial portion of, compacted sediment and this material increases in density with increasing depth. As a consequence, the situation can arise where the keel 4 (which projects downwardly below the level of the tip 6) experiences an upward resisting force as it moves through the increasingly compact sediment. This upward force is capable of directing the tip 6 upwardly and therefore drives the fluke 3 upwardly towards the seabed 7, rather than downwardly as intended. The result of this action is that the anchor 1 does not properly engage with the seabed 7 but instead ploughs a furrow in the seabed 7.

[0049] Turning now to Figs. 3-5, the anchor 11 of the first embodiment has an arcuate shank 12 and a fluke 13 which includes a keel 14 and a tip 16. The fluke 13 has a shape resembling that of a bicycle seat and also includes an upstanding lug 17 to which the shank 12 is pivoted by means of a resiliently loaded pivot 20. The shank has a pair of cheeks 19 and the lug 17 has a pair of cheeks 18. In Fig. 5 only one cheek of each pair of cheeks is illustrated. As seen in Fig. 5, the resiliently loaded pivot 20 includes aligned apertures 22, 23 through which a rivet 21 passes. Adjacent the rivet 21 are two pairs of abutments 24 which limit the motion of the shank 12 towards the tip 16.

[0050] In Fig. 5, the cheeks 18, 19 closer to the viewer have been removed from the drawing in order to illustrate the interior components. Thus, it can be seen that the shank 12 has a stop flat 25 whilst the lug 17 has a stop flat 26. A helical spring 28 surrounds a connecting rod 29 which has a hole 30 in its upper end and an elongate closed slot 31 in its lower end. A first pin 33 passes through an opening 34 in the shank 12 and through the hole 30. The first pin 33 is positioned above the upper end of the spring 28. A second pin 36 passes through an opening 37 in the lug 17 and also through the slot 31. In addition, the second pin 36 passes below the lower end of the helical spring 28. As a consequence of this construction, the shank 12 can resiliently pivot relative to the lug 17 but only within a limited range of movement. The movement of the shank 12 away from the tip 16 is set by the length of the slot 31 and the length of the connecting rod 29. This movement is resiliently loaded by the helical spring 28 and limited also by the length of the connecting rod 29 relative to the position of the stop flats 25, 26. The limit of movement of the shank 12 towards the tip 16 is set by the abutments 24.

[0051] It will be apparent from the foregoing that the rivet 21 constitutes a pivotal axis which is substantially perpendicular to the longitudinal axis of the fluke 13 about which the shank 12 is able to rotate. This rotation is resiliently loaded and preferably limited. The resiliently loaded pivot 20 is robust and able to withstand the forces applied to the shank 12.

[0052] As seen in Fig. 6, when no force is applied to the anchor 11, the helical spring 28 is not compressed (as best seen in Fig. 7) and the fluke 13 presents an angle of attack B of approximately 10-15°. However, as seen in Figs. 8 and 9, the fluke 13 can pivot relative to the shank 12 so as to compress the helical spring 28. This movement is limited by the abutment of the connecting rod 29 with the stop flats 25, 26. In this configuration the fluke 13 presents an angle of attack C of approximately 25-30°.

[0053] As a consequence of this situation, the anchor 11 is also able to right itself from a condition similar to that illustrated in Fig. 2 into the intended upright position illustrated in Figs. 10 and 11. However, as the anchor 12 moves through the sediment of the seabed 7, so sediment begins to build up on the upper surface of the fluke 13 thereby steadily increasing the compression of the spring 28 and increasing the angle of attack of the tip 16 of the fluke 13. As a result of this movement, the keel 14 does not protrude below the tip 16 and does not experience the abovementioned hydraulic forces exerted by the uncompacted sediment. As a consequence, the anchor 11 does not plough a furrow through the seabed 7 but instead digs deeper and deeper into the sediment thereby resulting in a holding engagement between the anchor 11 and the seabed 7.

[0054] Furthermore, as a safety measure, in the event that the spring 28 disintegrates in a fatigue fracture, for example, the movement of the shank 12 relative to the fluke 13 is constrained by the abutments 24 and stop flats 25, 26. Thus a failure of the resiliently loaded pivot 20 does not result in a catastrophic failure of the anchor 11.

[0055] Turning now to Figs. 12-15, an anchor 111 of a second embodiment is illustrated. The fluke 13 and keel 14 are as for the embodiment of Figs. 3-11. However, the lug 117 is extended upwardly and includes a nose 150. A shank 112 is cut from sheet spring steel so as to have two arms 151, 152 which are joined by a bight 153. The conventional anchor rode (not illustrated) is attached to the bight 153 by means of a suitable link 154. The lower arm 152 at its free end is bifurcated and pivoted on the lug 117 by means of a rivet 161. The upper arm 151 at its free end is pivoted to the upper end of a link 165 by means of a rivet 162. The lower end of the link 165 is pivoted to the lug 117 by means of a rivet 163.

[0056] As a consequence of this arrangement, a force applied to the bight 153 by the rode and having a downward component, pivots the shank 112 downwardly. This pivotal movement is stopped by the abutment of the upper arm 151 with the nose 150. This is the position illustrated in Figs. 12-14 and in this configuration the fluke 13 has an angle of attack of approximately 10-15°. This facilitates the tip 16 biting into the seabed sediment as in the first embodiment. However, as this biting engagement continues, so the rode progressively applies an upwardly directed force component to the bight 153 which results in the shank 112 rotating in an anticlockwise direction as seen in Fig. 15 so as to increase the angle of attack. This movement continues until the lower arm 152 engages with the nose 150 as illustrated in Fig. 15. In this condition the angle of attack is approximately 30°. Thus, it will be seen that the anchor 111 has a resiliency loaded action as provided by the arms 151, 152 and the pivoted link 165. This is analogous to the resiliently loaded pivot 20 of the anchor 11.

[0057] An advantage of the anchor 111 is that the link 154 can be moved towards the nose 150 by the action of the rode during retrieval of the anchor, thereby permitting the rode to be substantially aligned with the longitudinal axis of the fluke 13. This has the consequence that a rearward removal force is applied to the anchor 111. This facilitates removal of the tip 16 from underneath a rock or chain, for example.

[0058] Turning now to Figs. 16-19, an anchor 211 of a third embodiment is illustrated having a shaft 212, a single fluke 213 and a keel 214. The fluke 213 has a tip 216. The keel 214 has a through hole 217 which receives a pin 218 about which the shank 212 can pivot. The pin 218 has a head 219 and an internally threaded shaft which receives a screw 212. In addition to passing through the through hole 217, the pin 218 also passes through an aperture 222 in the shank 212.

[0059] As best seen in Fig. 23, the fluke end 225 of the shank 212 is provided with an upstanding boss 226 which is shaped to mate with one end of a helical spring 227. In addition, the fluke end 225 is provided with a lug 228 which has a threaded blind hole (obscured) which receives a bolt 229 (Fig. 19).

[0060] As seen in Figs. 20-22, the spring 227 receives an internally threaded bolt 231 having a head 232 with an aperture 233 leading into the interior of the bolt 231. The interior of the bolt 231 receives a grub screw 235 having an Allen key socket 236 at one end. As seen in Fig. 22, with the grub screw 235 received in the bolt 231, both the bolt 231 and the grub screw 235 are received within the interior of the helical spring 227. By inserting an Allen key (conventional but not illustrated) into the aperture 233, the Allen key can be used to rotate the grub screw 235 and thus adjust its position relative to the spring 227. In this way the maximum degree of compression of the spring 227 can be adjusted.

[0061] As seen in Fig. 19, the fluke 213 has a recess 240 which receives the spring assembly of Fig. 22 which in turn engages with the lug 226 (Fig. 23). The pin 218 passes through the through hole 217 and the aperture 222 to complete the assembly of the pivoting arrangement for the shank 212. As the bolt 229 is engaged with the boss 228, this restrains the clockwise rotation of the shank 212 since the bolt 229 comes into contact with the fluke 213. The shank 212 can pivot relative to the fluke 213 in the anticlockwise direction with the maximum range of the pivoting action being determined by the relative position of the grub screw 235 within the bolt 231.

[0062] As best seen in Figs. 23 and 24, the fluke end 225 of the shank 225 is provided with a multiplicity of ramped protrusions 241. With the movement of the shank 225 relative to the recess 240, so the ramped protrusions 241 swish water back and forth through the recess 240, thereby washing any debris out of the recess 240 and keeping it clear.

[0063] Turning now to Figs. 25-29, it will be seen from Fig. 27 that raising the shank 212, or rotating it in an anticlockwise direction, has the effect of increasing the angle of attack of the fluke 213. Thus, if the anchor is tending to move to the right as seen in Figs. 25-29, then this increased angle of attack results in the anchor becoming more firmly embedded in the seabed 7. This is because a greater effective vertical surface of the fluke 213 is available to resist the horizontal force to the right being applied to the shank 212 by the rode 8. Also the tilting of the keel 214 means it is behind the tip 216 and thus is not exerting an upward pressure on the fluke 213. The net effect is to move the anchor 211 from the position illustrated in Figs. 25 and 27 into the position illustrated in Figs. 26 and 29.

[0064] Figs. 30 and 31 illustrate a second embodiment of the spring assembly in which the helical spring 227 is as before, however, the bolt 231 and grub screw 235 are replaced by a bolt 331, a rod 335 and a stop 332. The arrangement again limits the degree of compression of the spring 227.

[0065] As seen in Figs. 32 and 33, the bolt 229 can be replaced by an eyebolt 339 to which an auxiliary chain 343 can be used to attach a second anchor 211 in a ganged arrangement as illustrated in Figs. 33. This is particularly of assistance in holding larger vessels in soft seabeds. In Fig. 34, four arrangements are illustrated to scale so as to show the effect of shortened rodes 8, and rodes 8 under tension. It will be seen that under normal circumstances the rode 8 forms a catemary and, in particular, the portion of the rode 8 closest to the anchor 111, 211 lies on the seabed 7. Thus, the situation is as illustrated in Figs. 25 and 27. However, as the wind and / or the swell rise, so the rode 8 is under increased tension and flattens so as to form an essentially straight line. As illustrated in the second of the Figs. 34 drawings, the tensioned rode 8 has the effect of raising the shank 112, 212. This decreases the angle of attack of the anchor 111, 21 Irelative to the seabed 7.

[0066] The scope of the mooring set up is the ratio of the length of the rode 8 to the depth of the water above the seabed 7. Ideally the scope should be approximately 8 or more, however, scopes in the range of 5-7 are generally regarded as being acceptable. This is as illustrated in the first two drawings of Fig. 34.

[0067] However, circumstances often arise where deep water and / or a crowded mooring area mean that scopes of 3-5 are often obliged to be used in practice. As seen in the third and fourth drawings of Fig. 34, with a scope of 4 the situation can arise, as a result of high winds and / or swell, that the rode 8 under tension makes an angle of approximately 13-15° with the seabed 7. With the conventional prior art anchor 1 illustrated in Figs. 1 and 2, for example, this means that the angle of attack is (10-15°) minus (13-15°) which is near zero or negative. This means that the anchor 1 disengages from the seabed 7 and the moored vessel is placed in considerable danger.

[0068] This is to be contrasted with the present invention where, as seen in Figs. 11 and 26, the initial angle of attack with a raised shank 112, 212 is approximately 30°. If this is reduced by the (13-15°) indicated in Fig. 34 then the fluke 113, 213 still retains a healthy angle of attack relative to the seabed 7. Thus, the anchor 111, 211 does not disengage from the seabed 7.

[0069] The foregoing describes only some embodiments of the present invention and modifications, obvious to those skilled in the marine anchor arts, can be made thereto without departing from the scope of the present invention. For example, the features and advantages disclosed in one facet of the invention may be utilised, mutatis mutandis, in other facets of the invention.

[0070] The term “comprising” (and its grammatical variations) as used herein is used in the inclusive sense of “including” or “having” and not in the exclusive sense of

[0071] “consisting only of’.

Claims

CLAIMS1. A resilient marine anchor having a single fluke with a longitudinal axis and a generally V-shaped tip, said fluke having an upper surface and a keel protruding from a lower surface of said fluke and aligned with said longitudinal axis, a shank pivotably mounted to said fluke about a pivot axis substantially perpendicular to said fluke longitudinal axis and movable relative thereto to change the angle of attack of said anchor, and a resilient means extending between said shank and said fluke and arranged to resiliently load the pivotal movement of said shank relative to said fluke.

2. The marine anchor as claimed in claim 1 wherein said resilient means includes stops to limit the extent of the change of angle of said angle of attack.

3. The marine anchor as claimed in claim 2 wherein said angle of attack is movable between a first range of 10-15° and a second range of 25-30°.

4. The marine anchor as claimed in any one of claims 1-3 wherein said resilient means comprises a spring.

5. The marine anchor as claimed in claim 4 wherein said spring is a helical spring.

6. The marine anchor as claimed in any one of claims 1-5 wherein the shape of said fluke resembles a bicycle seat.

7. The marine anchor as claimed in any one of claims 1-6 wherein said shank is arcuate .

8. The marine anchor as claimed in any one of claims 1-7 wherein said fluke has an upstanding lug to which said shank connected.

9. The marine anchor as claimed in claim 8 wherein said shank comprises a pair of arms extending from a bight.

10. The marine anchor as claimed in claim 9 wherein said shank is formed from spring steel.

11. The marine anchor as claimed in any one of claims 8 - 10 wherein said lug is extended to lie between said arms and has a nose which constitutes a stop means to limit the pivotal movement of said shank relative to said fluke.

12. The marine anchor as claimed in any one of claims 1-7 wherein said fluke has a recess in its upper surface which receives said shank.

Images